Given an integer N, the task is to find the sum of numbers from 1 to N which are in Fibonacci sequence.
First few Fibonacci numbers are 1, 1, 2, 3, 5, 8, 13, 21, 34, ….
Examples:
Input: N = 5
Output: 12
1 + 1 + 2 + 3 + 5 = 12
Input: N = 10
Output: 20
1 + 1 + 2 + 3 + 5 + 8 = 20
Approach:
- Loop through all the Fibonacci numbers which are less than N.
- Initialize a sum variable with 0.
- Keep on adding these Fibonacci numbers to get the required sum.
Below is the implementation of the above approach:
C++
// C++ implementation of the approach #include <bits/stdc++.h> using namespace std; // Function to return the // required sum int fibonacciSum(int N) { if (N == 0) return 0; // Generate all Fibonacci numbers <= N // and calculate the sum int sum = 0; int a = 1, b = 1, c; sum += a; while (b <= N) { sum += b; int c = a + b; a = b; b = c; } return sum; } // Driver code int main() { int N = 20; cout << fibonacciSum(N); return 0; } |
Java
// Java implementation of the approach class GFG { // Function to return the // required sum static int fibonacciSum(int N) { if (N == 0) return 0; // Generate all Fibonacci numbers <= N // and calculate the sum int sum = 0; int a = 1, b = 1, c; sum += a; while (b <= N) { sum += b; c = a + b; a = b; b = c; } return sum; } // Driver code public static void main(String[] args) { int N = 20; System.out.println(fibonacciSum(N)); } } // This code is contributed by Code_Mech. |
Python3
# Python3 implementation of # the approach # Function to return the # required sum def fibonacciSum(N): if N == 0: return 0 # Generate all Fibonacci # numbers <= N and calculate # the sum Sum = 0 a, b = 1, 1 Sum += a while b <= N: Sum += b a, b = b, a + b return Sum # Driver code if __name__ == "__main__": N = 20 print(fibonacciSum(N)) # This code is contributed # by Rituraj Jain |
C#
// C# implementation of the approach using System; class GFG { // Function to return the // required sum static int fibonacciSum(int N) { if (N == 0) return 0; // Generate all Fibonacci numbers <= N // and calculate the sum int sum = 0; int a = 1, b = 1, c; sum += a; while (b <= N) { sum += b; c = a + b; a = b; b = c; } return sum; } // Driver code public static void Main() { int N = 20; Console.WriteLine(fibonacciSum(N)); } } // This code is contributed by Code_Mech. |
PHP
<?php // PHP implementation of the approach // Function to return the // required sum function fibonacciSum($N) { if ($N == 0) return 0; // Generate all Fibonacci numbers <= N // and calculate the sum $sum = 0; $a = 1; $b = 1; $c; $sum += $a; while ($b <= $N) { $sum += $b; $c = $a + $b; $a = $b; $b = $c; } return $sum; } // Driver code $N = 20; echo(fibonacciSum($N)); // This code is contributed // by Code_Mech. ?> |
Javascript
<script> // Javascript implementation of the approach // Function to return the // required sum function fibonacciSum(N) { if (N == 0) return 0; // Generate all Fibonacci numbers <= N // and calculate the sum var sum = 0; var a = 1, b = 1, c; sum += a; while (b <= N) { sum += b; var c = a + b; a = b; b = c; } return sum; } // Driver code var N = 20; document.write( fibonacciSum(N)); </script> |
Output:
33
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